Sumiko Odani

Effects of a High-Pressure Treatment on Bovine Gamma Globulin and Its Reduction in Allergenicity

The effects of a high-pressure treatment on the IgE-specific binding activity and structural changes to bovine gamma globulin (BGG), a beef allergen, were investigated. The allergenicity of pressure-treated BGG was also evaluated. We found that the IgE-specific binding activity and allergenicity of BGG were decreased by the high-pressure treatment. Almost no significant change in secondary structure was apparent for pressurized BGG, but a change in the tertiary structure was detected. The decreased IgE-specific binding activity and allergenicity of pressurized BGG were probably due to changes in the tertiary structure caused by pressurization. The results of this study suggest that a high-pressure treatment would be an effective food-processing technique to reduce the allergenicity of BGG.

Ribonuclease Inhibitors in Malus x domestica (Common Apple): Isolation and Partial Characterization

A ribonuclease inhibitory activity was detected in the fruits of common apple, Malus x domestica, cv. Fuji, and purified by affinity chromatography on ribonuclease A-Sepharose. It inhibited hydrolysis of cyclic-2′:3′-CMP by bovine pancreatic ribonuclease A with an apparent inhibition constant of about 5×10-8 M. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of the purified protein gave two peaks corresponding to the mass numbers of 55,658 and 62,839, while three bands of 43-, 34-, and 21-kDa were detected by SDS-PAGE. These results suggested that the inhibitor preparation was a mixture of two proteins comprised of 43- and 21-kDa subunits or of 34- and 21-kDa subunits. Attempts to separate these two proteins were unsuccessful. Amino acid composition and N-terminal amino acid sequence of these subunits were also identified and N-terminal sequences showed some similarity to that of cottonseed storage globulin. The significance of the presence of ribonuclease inhibitors in apple fruits is not clear, but it might allow some speculation about their possible involvement in the control of the self-incompatibility ribonuclease of Rosaceae plants.